MTS 318 Load Unit - Manual (Page 64)

318 Load Unit 64 Operation
The crosshead can slowly drift down the columns if the locks are turned off
and when hydraulic pressure is turned off.
The crosshead can damage any test fixtures, grips, and specimen in its
path.
Unlock the crosshead only to reposition it. Always lock the crosshead after you
have repositioned it, and never leave the crosshead unlocked.
2. Set the crosshead position.
The crosshead position depends on the length of the specimen being tested,
the starting position of the actuator, and the size of the fixtures or grips
being used.
3. Install the specimen.
Specimen installation varies according to the type of grip being used. See
the appropriate grip manual for installation instructions. MTS manufactures
a variety of grips:
• The Series 641 Hydraulic Wedge Grips (hydraulically controlled) are
specifically designed for static or fatigue testing applications. They are
available with a self aligning feature. These are hydraulically
controlled grips.
• The Series 643.6X Tension/Compression Grips (mechanical) are used
for testing threaded-end and button-end specimens in tension,
compression, or tension/compression.
• The Series 646 Hydraulic Collet Grips (hydraulically controlled) are
designed to perform in a wide variety of testing applications (for
example, high and low cycle fatigue, tension, and compression).
• The Series 647 Hydraulic Wedge Grips (hydraulically controlled) are
specifically designed for static or fatigue testing applications. There are
a variety of configurations of this grip.
• The Series Advantage Wedge Grips are specifically designed for static
or fatigue testing applications. These are a mechanical version of the
Series 647 Hydraulic Wedge Grips.
• Specialty grips (mechanical) are designed to grip specific types of
material such as string, tread, tendons, etc.
Each type of grip requires the specimen or specimen fixture to fit properly
into the grip. You should always review specimen installation procedures
found in any grip product information manual.
CAUTION